Why are novels laid out the way they are? It's almost as though its not as simple as "bad for reading" but rather a feature of the content.
imo it highly depends on the medium. If your content is packed with distracting ads, flashing banners, other unrelated text from other stories, then its helpful to make the columns narrow to help you scan.
If you have a more focused experience around one passage of text, wider text lets you fit more on the page and make better use of paragraph breaks and subheadings
Video games are routinely stomping over all known rules of good user interface in the name of art. And that's okay because it's a leisure activity, and efficiency and comfort is not the goal. I suspect the same thing is true of novels - making the text physically easier to read wouldn't make the story emotionally easier to enjoy, so they intentionally choose a suboptimal text layout for aesthetic reasons.
The only two types of books I can think of that are routinely read for purposes other than leisure - dictionaries and the Bible - are usually printed in multi-column layout from what I've seen.
Cost has always been a major factor in publishing fiction. 25% fewer words per line may boost comprehension by $x% but definitely increases cost by 25%. When markets are as price sensitive as leisure, cost is a big factor in the decision. Books don’t sell on a price per printed page basis. Mainstream publishers with existing distribution contracts are especially sensitive because of print runs.
When we published a print magazine we optimized heavily to save 1% on printing costs. 25% would have been suicide. And indie magazine buyers are traditionally a lot more price flexible than mainstream book buyers.
imo it highly depends on the medium. If your content is packed with distracting ads, flashing banners, other unrelated text from other stories, then its helpful to make the columns narrow to help you scan.
If you have a more focused experience around one passage of text, wider text lets you fit more on the page and make better use of paragraph breaks and subheadings